Gov. Michael S. Dukakis announced Tuesday he would not seek re-election in 1990 to another term in the Massachusetts Statehouse.

"This will be my last term as governor of Massachusetts," he said.The three-term Democrat, the unsuccessful 1988 presidential candidate, gave no immediate indication of his long-term plans, including whether he would drop out of politics altogether or seek the presidency again in 1992. He said he would announce his plans later this week.

He said he intended to spend the next two years fulfilling his responsibilities and wrapping up his programs.

Dukakis said his loss in the presidential race had little impact on his decision. Even if he had not run for president, he probably would have decided not to seek a fourth four-year term, he said.

In recent weeks, Dukakis had been urged by fellow Democrats to announce his plans so they could begin making their political plans for the governorship.

"One has to make a decision; I've made that decision," he said.

"It seemed to me desirable to make the decision now, rather than later," he added.